TY - JOUR A1 - Whitcomb, Sarah J. A1 - Nguyen, Huu Cuong A1 - Brückner, Franziska A1 - Hesse, Holger A1 - Hoefgen, Rainer T1 - CYSTATHIONINE GAMMA-SYNTHASE activity in rice is developmentally regulated and strongly correlated with sulfate JF - Plant science : an international journal of experimental plant biology N2 - An important goal of rice cultivar development is improvement of protein quality, especially with respect to essential amino acids such as methionine. With the goal of increasing seed methionine content, we generated Oryza sativa ssp. japonica cv. Taipei 309 transgenic lines expressing a feedback-desensitized CYSTATHIONINE GAMMA-SYNTHASE from Arabidopsis thaliana (AtD-CGS) under the control of the maize ubiquitin promoter. Despite persistently elevated cystathionine gamma-synthase (CGS) activity in the AtD-CGS transgenic lines relative to untransformed Taipei, sulfate was the only sulfur-containing compound found to be elevated throughout vegetative development. Accumulation of methionine and other sulfur-containing metabolites was limited to the leaves of young plants. Sulfate concentration was found to strongly and positively correlate with CGS activity across vegetative development, irrespective of whether the activity was provided by the endogenous rice CGS or by a combination of endogenous and AtD-CGS. Conversely, the concentrations of glutathione, valine, and leucine were clearly negatively correlated with CGS activity in the same tissues. We also observed a strong decrease in CGS activity in both untransformed Taipei and the AtD-CGS transgenic lines as the plants approached heading stage. The mechanism for this downregulation is currently unknown and of potential importance for efforts to increase methionine content in rice. KW - Aromatic amino acids KW - AtD-CGS KW - Branched chain amino acids KW - CYSTATHIONINE GAMMA-SYNTHASE KW - Glutathione KW - Oryza sativa ssp japonica cv. taipei 309 KW - Sulfate Y1 - 2018 U6 - https://doi.org/10.1016/j.plantsci.2018.02.016 SN - 0168-9452 VL - 270 SP - 234 EP - 244 PB - Elsevier CY - Clare ER - TY - JOUR A1 - Nabhan, Sami A1 - Luber, Tim A1 - Scheffler, Franziska A1 - Heubeck, Christoph T1 - Climatic and geochemical implications of Archean pedogenic gypsum in the Moodies Group (similar to 3.2 Ga), Barberton Greenstone Belt, South Africa JF - Precambrian research N2 - Lithic sandstones of braided-fluvial to supratidal facies in the Paleoarchean Moodies Group (similar to 3.22 Ga, Barberton Greenstone Belt, South Africa) include several regionally traceable units with common to abundant, in places rock-forming, nodular concretions of megaquartz pseudomorphs after gypsum, barite and calcite. Concretionary accumulations are stratiform and commonly associated with aqueously reworked, fine-grained, tuffaceous sediment of originally rhyodacitic composition and can grow to fist sized agglomerates in crusts tens of m in lateral extent. Weathering of tuffaceous material and feldspar delivered alkali cations such as Ca, Ba, and K, while carbonates were likely supplied by silicate weathering of mafic to ultramafic volcanic rocks during exposure to a CO2-rich atmosphere. Sulfate ions were partly delivered by oxidative pyrite dissolution which may have included microbial and abiotic disproportionation of volcanic S or SO2. Concretionary growth apparently took place under pedogenic to early diagenetic conditions within unconsolidated granular sediment in the vadose zone, dominated by seasonal fluctuations of the groundwater level under evaporitic conditions. The concretions likely represent the oldest terrestrial evaporites known to date and form part of the oldest known compound paleosols. Their formation and composition constrain the local occurrence of sulfate in the Archean atmo- and hydrosphere, their interaction with the emerging biosphere, Archean weathering regime, local climate, and vadose-zone hydrodynamics. (C) 2016 Elsevier B.V. All rights reserved. KW - Barberton Greenstone Belt KW - Archean KW - Moodies Group KW - Evaporites KW - Sulfate KW - Paleosol Y1 - 2016 U6 - https://doi.org/10.1016/j.precamres.2016.01.011 SN - 0301-9268 SN - 1872-7433 VL - 275 SP - 119 EP - 134 PB - Elsevier CY - Amsterdam ER -